The pre-condition steps generated by the `install`/`git-repos` directives
where only rendered for automated testcases. Arguably, manual testers are
more interested in those being rendered than LAVA, which usually considers
the YAML enough as-is.

This currently affected the WebKit manual testcases such as
webkit2gtk-ac-3d-rendering.yaml where no installation pre-condition was
rendered, omitting fundamental steps needed by manual testers.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>